Traumatic brain injury (TBI) remains a significant cause of death and disability in its own right in the United States and is an important risk factor for other neurodegenerative conditions. However, there are currently no approved therapies for TBI and its long term consequences are difficult to predict. More than 30 major phase III trials have failed without a single success so discovery of a universal therapy seems increasingly unlikely. NINDS and other federal agencies have committed tens of millions of dollars to large, observational, human studies of TBI. These studies are genotyping and deeply phenotyping TBI patients with the goal of personalizing therapy. These efforts have already revealed fascinating correlations between genotype and TBI outcome. However, genes cannot be switched on an off in humans for ethical reasons. Therefore, new tools are necessary to move from detecting correlations to testing hypotheses. This challenge has been addressed in other diseases using human, in vitro models. Human neurons generated from patients using stem cell technology retain the genetic identity of the patient. Also, genetic variants can be changed one at a time in these cells. Therefore, hypotheses about the role of genotype in disease can be tested in human, in vitro models but only if the disease pathology can reproduced in vitro. Reproducing neurotrauma pathology in vitro requires special tools because it depends intrinsically on a mechanical insult. The goal of this proposal is to provide new tools for modeling neurotrauma in vitro that can take advantage of exciting recent developments in human, in vitro cultures. Target-driven drug discovery is difficult in neurotrauma because the molecular mechanisms are complex. Phenotypic drug discovery is therefore preferable but it can succeed only if it addresses a clinically relevant phenotype. In vitro, electrical field recordings are attractive because they are analogous to electroencephalography, which is commonly used to assess TBI patients. This work will contribute the first, multi-electrode array (MEA) that can acquire field recordings from a high throughput, in vitro model. Brain organoids reproduce aspects of disease that cannot be reproduced in 2D cultures. However, electrical field recordings are difficult to acquire from brain organoids because conventional, multi-electrode arrays are designed for adherent cultures while brain organoids require ultra-low adherence conditions. Therefore, novel, sub-millimeter scale structures are proposed that will enclose an organoid inside an array of electrodes without adhering to it so that long term measures of electrical activity and connectivity can be made. These 3D MEAs will contribute new insights to many neurological disorders beside neurotrauma. Currently, there are no tools available that can apply a biofidelic, mechanical insult to an organoid culture. The proposed work will develop such a tool. In combination, these new tools will open new horizons in the field around personalizing therapy, probing disease mechanism and offering patient-specific risk assessment.